Spring feeder plate

ABSTRACT

An improved spring feeder for sheet feeders of the reciprocating bottom-feed type arranged to extend from a conventional spring feeder bar toward adjacent processing machinery rather than away from such machinery resulting in a more positive engagement with the sheet during the feed stroke. The spring feeder includes a plate mountable to a feeder bar reciprocating beneath a stack of sheets. The plate has a first end attached to the bar and a second end inclined upwardly toward the bottom of the stack. The second end includes a lip portion secured to the plate for engaging successive bottom sheets of the stack and for pushing the sheets toward adjacent processing machinery. The plate may be either flexible or rigid and pivotally spring loaded to maintain an upward pressure against the bottom of the stack.

United States Patent Haas [4 1 Aug. 1, 1972 SPRING FEEDER PLATE Primary Examiner-Joseph Wegbreit [72] Inventor; James P'HaasBaltimore Attorney-:Boyce C. Dent, Oscar B. Brumback and i Olin E. Williams 1 [73] Assrgnee: Koppers Company Inc. 22 Filed: Dec. 31, 1970 [57] ABSTRACT,

An improved spring feeder for sheet feeders of the [211 Appl' 103l68 reciprocating bottom-feed type arranged to extend from a conventional spring feeder bar toward adjacent [52] U.S.-Cl. .;27l/44R processing machinery rather than away from such [51] Int.Cl... ..B6Sh 3/24 ma y'r ulting in a m re p sitiv ngagement [58] Field of Search ..271/44 with the sheet r g the feed o ehe spring feeder includes a plate mountable to a feeder bar 56] R f rence Ci reciprocating beneath a stack of sheets. The plate has g a first end attached to the bar and a second end UNITED STATES PATENTS inclined upwardly toward the bottom of the stack. The second end includes a lip portion secured to the plate 3 g for engaging successive bottom sheets of the stack and 1236054 8/1917 Cl i 'T [4 4 for pushing the sheets toward adjacent processing 11/1872 i" 44 R machinery. The plate may be either flexible or rigid 2 1 1942 F 7 and pivotally spring loaded to maintain an upward l I i)? g pressure against the bottom of the stack.

2 Claims, 12 Drawing Figures PATENTEDAus 1 I572 3.680.858 sum 2 BF 2 FIG. 3 (Prior Ari) Prior An) a 7 3M FIG. 8

(Prior Art) FIG. INVENTOR.

JAMES R HAAS SPRING FEEDER PLATE CROSS REFERENCE TO RELATED APPLICATIONS This invention relates generally to the pivotally mounted spring feeder structure disclosed in co pending application Ser. No; 78421 filed on Oct. 6, 1970 by Gordon M. Spicer entitled Torsionally Spring Loaded Feeder Plates, and assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention:

This invention relates generally to feeding and more particularly to separators of the reciprocating bottom feed type.

2. Description of the Prior Art:

During the processing of corrugated paperboard, blanks or sheets are formed to be made into various sized containers. Stacks of the sheets are singly fed into processing machinery where cutting, scoring and printing-operations are usually performed. Generally, the

sheets are fed from the 'bottom of the stack by a reciprocating feeder. 'bar which has several flexible spring feeder plates mounted laterally along the bar. The feeder plates have a raised lip portion at their trailing edges for engaging the trailing edge of each sheet. The weight of the stack constantly flexes or loads the feeder plates thereby constantly exposing the plates to varying forces.

Conventionally, feeder plates are substantially flexible and are rigidly attached to a feeder bar. However, rigid feeder plates may be resiliently attached to the feeder bar so as to pivot with respect to the bar rather than flexing or bending. Both theconventional flexible and the rigid feeder plates are mounted to extend from the feeder bar away from the feed end where the adjacent processing machinery is located. As the feeder bar moves toward the feed end, conventional sheet feeders essentially pull the sheets from the bottom of the stack since the point where the plate attaches to the bar leads the point where the lip portion engages the trailing edge of the sheet. An example of a conventional, flexible spring feeder having improved flexing characteristics is shown and described in Barnes U.S. Pat. No. 3,409,289; Palamenti U.S. Pat. No. 3,265,386 illustrates a conventional spring feeder.

This conventional arrangement has disadvantages during both the feed stroke and the return stroke of the feeder bar.

The resultant force acting on the plate at the beginning of the forward or feed stroke is in part due to inertial and frictional resistance of the sheet and the acceleration of the bar. This resultant force tends to urge the plate clockwise, as viewed in FIG. 2, about the point of attachment of the plate to the bar and generally downward away from the stack, that is, it tends to flatten the plate toward the bar. Therefore, the lip portion which is at the raised trailing end of the conventional plate tends not to be urged into firm engagement with the trailing edge of the sheet but tends to become disengaged therefrom. As a result, the lip portion on one or more of the plates may miss the trailing edge of the sheet thus causing the sheet to become skewed, or the lip portion may scarcely engage the trailing edge and thus tear a portion of the bottom liner of the sheet being fed.

The resultant force acting on the plates at the beginning of the return stroke, when the bar is moving away from the feed end, is in part due to the high acceleration force and the resilient flexing 0f the plate. Therefore, this resultant force tends to urge the plate counter-clockwise about the point of attachment and generally upwardly toward the bottom of the stack.

Therefore, at the beginning of the feed stroke the forces acting on the plate tend to force the plate downward and out of firm engagement with the trailing edge of the sheet being fed, and at the beginning of the return stroke the forces acting on the plate tend to force the plate upward into the bottom of the stack.

SUMMARY OF THE INVENTION The present invention contemplates feeder plates mounted on a feeder bar and extending toward the feed end and the adjacent processing machinery. Therefore, during the feed stroke of the bar, the raised end of the plate, which includes the lip portion for engaging the trailing edge of the sheets, is ahead of or leads the attached end of the plate as the feeder bar moves toward the feed end. During the return stroke the feeder bar moves away from the feed end, and the portion of the plate which is attached to the bar leads the raised end portion.

Therefore, at the beginning of the feed stroke, the combined forces of acceleration and the resistance of the sheet being fed tend to urge the raised edge of the plate, including the lip portion, clockwise about the point of'attachment and generally upward into firm engagement with the trailing edge of the bottom sheet. Therefore, this novel sheet feeder tends to push the sheets from the bottom of the stack rather than pull the sheets as conventional sheet feeders usually do.

At the beginning of the return stroke the highly negative forces of acceleration urge the feeder plate counter-clockwise about the point of attachment and generally downward away from the bottom of the stack.

As'a result, more efficient feeding of the sheets is realized from the improved interaction between the feeder plate and the stack.

The above and further objects and novel features of the invention will appear more fully from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like parts are marked alike: FIG. 1 is a perspective view showing the arrangement of the novel spring feeders mounted on a feeder bar;

FIG. 2 is a diagrammatic illustration in side elevation of the conventional spring feeder apparatus in its usual environment; FIG. 3 is a diagrammatic illustration in side elevation of a prior art spring feeder having a flexible feeder plate attached to the front edge of a feeder bar and extending upward and backward from the direction of feeding;

FIG. 4 is a diagrammatic illustration in side elevation of another prior art spring feeder having a rigid feeder plate pivotally attached to the front edge of the bar and extending upward and backward from the direction of feeding;

FIG. Sis a diagrammatic illustration in side elevation of the novel spring feeder having a flexible feeder plate attached to the back edge of the bar and extending upward and forwardly toward the direction of feeding;

FIG. 6 is a diagrammatic illustration in side elevation of another embodiment of the novel spring feeder having a rigid feeder plate pivotally attached to the back edge of the bar and extending upward and forwardly toward the direction of feeding;

FIG. 7 is a diagrammatic illustration showing various forces acting on a prior art spring feeder at the beginning of the feed stroke;

FIG. 8 is a diagrammatic illustration showing various forces acting on a prior art spring feeder at the beginning of the return stroke; 7

FIG. 9 is a diagrammatic illustration showing various forces acting on the novel spring feeder at the beginning of the return stroke;

FIG. 9 is a diagrammatic illustration showing various forces acting on the novel spring feeder at the beginning of the feed stroke;

FIG. 10 is a diagrammatic illustration showing various forces acting on the novel spring feeder at the beginning of the return stroke;

FIG. 11 is a diagrammatic illustration showing the novel spring feeder plate attached to the top edge of the feeder bar; and

FIG. 12 is a diagrammatic illustration showing the novel spring feeder plate attached to the forward edge of the feeder bar.

DESCRIPTION OF THE PREFERRED EMBODIMENT A conventional sheet feeder assembly of the reciprocating bottom-feed type is generally designated by numeral 10, in FIG. 2, and includes feed table 12, upon which a plurality of backstops 14 are supported by a laterally extending bar 15. The backstops 14 each include a ledge 16 for supporting the back or trailing edge of a stack of sheets 18. The leading edge of the sheets rest upon feed table 12. A gate 20 defines an opening 21 with feed end pull rolls 22 for metering the sheets 18, one at a time, between rolls 22. A feeder bar 30 reciprocates along the top of table 12. A plurality of spring feeders, such as those designated by numeral 31 in FIG. 3 are spaced across feeder bar 30. A lip portion 50 on each feeder 31 engages the trailing edge of the bottom sheet 18 at the end of the return stroke and urges the sheet forward during the feed stroke. The direction of feed to adjacent processing machinery is indicated by arrow 26. Feeder bar 30 moves in the direction indicated by arrow 26 during the feed stroke and in a direction indicated by arrow 28 during the return stroke, see FIG. 2.

Prior art feeder plates may be of the flexible type rigidly mounted to bar 30, FIG. 3, or of the rigid type pivotally attached to bar 30 by a resilient mounting 42 as shown in FIG. 4. Likewise, the feeder plates of this invention may be of either the flexible or rigid type as shown in FIGS. 5 and 6.

To overcome the tendency of the plate to flatten out during the feed stroke, which in effect tends to disengage the lip portion from the trailing edge of the blank, the natural solution would be to stiffen the flexible plate or increase the spring force tending to raise the rigid plate. This would, of course, tend to increase the engaging force between the lip portion and the trailing edge of the blank.

The present invention overcomes the tendency of the feeder plate to flatten out without stiffening the flexible plate or increasing the spring force. The forces acting on the plate are utilized in the present invention to cause the feeder plate to engage the trailing edge more firmly; the greater the force, the greater the tendency to engage.

This has been accomplished by arranging the feeder plate so that the lip portion of the feeder engages the trailing edge of the sheet ahead of, that is, toward the adjacent processing machinery, the connection of the feeder plate to the feeder bar. This results in the main forces acting on the plate, that is, the force of acceleration and the forces due to inertial and frictional resistance, tending to rotate the plate in a clockwise direction about the connection; thus, the forward end of the plate tends to rise into engagement with the trailing edge of the sheet during the feed stroke as the bottom sheet is pushed toward the feed end. This tendency is resisted by a downward force on the plate caused by the weight of the stack of blanks resting on it.

At the beginning of the return stroke of the feeder bar, the force of acceleration tends to raise the conventional feeder plate; that is, there is a tendency for it to rotate about its connection to the feeder bar.

When the spring feeder is used to feed sheets, various forces mentioned above act upon it during both the feed and return strokes of the feeder bar. FIG. 7 shows a force diagram illustrating some of the forces acting on a conventional spring feeder plate at the beginning of the feed stroke. FIG. 8 shows a force diagram illustrating some of the forces acting on a conventional spring feeder at the beginning of the return stroke. FIGS. 9 and 10 show force diagrams illustrating some of the forces acting on the novel spring feeder plates at the beginning of the feed and return strokes respectively. Although the same forces are present, the novel spring feeder plates of FIGS. 9 and 10 react differently to those same forces thus producing an improved interaction between the feeder plates and the sheets of the stack as will be subsequently explained.

The general arrangement of the novel spring feeder plates and feeder bar 30 is shown in FIG. 1.

FIGS. 3, 4, 5 and 6 illustrate spring feeder plates of either the flexible or rigid type for feeding sheets 18 into adjacent processing machinery (not shown) as in dicated by arrow 26 showing the direction of travel of bar 30 during the feed stroke.

The feeder plates shown in FIGS. 3 and 5 include flexible feeder plates 40F rigidly attached to feeder bar 30. A lip portion 50 is secured to the plate 40F adjacent its raised end portion in the conventional manner such as by riveting or welding (not shown). The leading edge 51 of lip portion 50 forms a nip with plate 40 for engaging the trailing edge of sheets 18, see FIG. 3.

The pivotal feeder plate arrangement illustrated in FIGS. 4 and 6 include a substantially rigid feeder plate 40R pivotally attached by resilient mounting 42 to bar 30, as specifically shown and described in co-pending application Serial Number 78,421 filed on Oct. 6, 1970 by Gordon M. Spicer. Plates 40R also include lip portion 50 for engaging the trailing edge of sheet 18.

FIGS. 3 and 4 illustrate the prior art types of flexible and rigid feeder plates 40F and 40R respectively, whereas FIGS. 5 and 6 illustrate the novel flexible and rigid feeder plates respectively.

Forces acting on feeder plate 40a, see FIG. 7, at the beginning of the feed stroke are substantially the same in the case of either'the prior art flexible plate or the novel flexible plate, see FIGS. 7 and 9. For example, some of the forces acting on plate 40a in FIG. 7 include the static weight of the plate indicated by arrow 44a, the'force of acceleration indicated by arrow 46a, the force imposed on lip 50a by sheet 180 indicated by arrow 47a and the resilient or flexing torque indicated by arrow 48a. Some of the forces acting on plate 40a of FIG. 9 include the static weight of the plate indicated by arrow 44a, the force of acceleration indicated by arrow 46a, the force imposed on lip 500 by sheet 18a indicated by arrow 47a and the resilient'or flexing torque indicated by arrow 48a. However, the main forces affecting the reaction of the plate are the force of acceleration of the feeder bar 30a being opposed by the inertial and frictional forces of the sheet.

During the feed stroke, forces acting on the conventional plate are substantially the same as those acting on the novel plate, see FIGS. 7 and 9. However, the moment produced by the resultant force causes a different result in each instance. These different results are due to the different physical relationship between the point of attachment of the plate to the bar, or pivot point, and the point of engagement of the lip and the sheet. That is, the moment indicated by arrow 49a in FIG. 7, produces a different result than the moment indicated by arrow 49a in FIG. 9.

Feeding the sheets produces a moment which tends to urge plate 40a and lip 50a upward intofirm engagement with the trailing edge of sheet 18a, see FIG. 9, thus overcoming some of the problems known in prior art feeders. Feeding the sheets with the conventional plates, as shown in FIG. 7, produces a moment which tends to urge plate 40a and lip 50a downward and out of engagement with the trailing edge of sheet 18a since the plate tends to rotate about its connection to the feeder bar 30a.

Similarly, forces acting on feeder plate 40b during the return stroke are substantially the same in the case of either the prior art rigid plate or the novel rigid plate, see FIGS. 8 and respectively. For example, some of the forces acting on plate 40b in FIG. 8 include the static weight of the plate indicated by arrow 44b, the force of acceleration indicated by arrow 46b, and the resilient or flexing torque indicated by arrow 48b. Some of the forces acting on plate 40b of FIG. 10 include the static weight of plate 405 indicated by arrow 44b, the force of acceleration indicated by arrow 46b and the resilient or flexing torque indicated by arrow 48b.

During the return stroke, forces acting on the conventional plate are substantially the same as those acting on the novel plate, see FIGS. 8 and 10. However, the moment produced by the resultant force causes a different result in each instance. These different results are due to the different physical relationship between the point of attachment of the plate to the bar, or pivot point, and the point of engagement of the lip and the sheet. That is,'the moment indicated by arrow 49b in FIG. 8, produces a different result than the moment indicated by arrow 49b in FIG. 10.

Forces acting on novel feeder plate 40b, FIG. 10, produce a moment during the return stroke of bar b which tends to urge plate b downward and away from the bottom of the stack, .whereas forces acting on conventional feeder plate 40b, FIG. 8, produce a moment during the return stroke of bar 30b which tends to urge plate 40b upward toward the bottom of the stack of sheets 18b.

Mounting of plate 40 to bar 30 is shown in FIG. 1. A plurality of feeder plates 40 are mounted to back edge 34 of bar 30 and extend toward the feed end adjacent the processing machinery (not shown). Sheet 18, shown in phantom outline, illustrates the relationship of the sheet being fed by novel spring feeders 40 in the direction of the feed stroke as indicated by arrow 26. Plate 40 can be the flexible type or the rigid type and may be attached to bar 30 along front edge 32, upper surface 36 or back edge 34, see FIGS. 11 and 12.

OPERATION In operation, feeder bar 30 rapidly reciprocates beneath a stack of sheets 18 feeding successive bottom sheets in the direction of the feed end to adjacent processing machinery (not shown). At the beginning of the feed stroke, the resultant force acting on the plate produces a moment which tends to urge lip portion clockwise about the point of attachment and generally upward into firm engagement with the trailing edge of bottom sheet 18. When bar 30 reaches the end of the feed stroke, the return stroke begins and bar 30 now moves away from the feed end. The resultant force acting on the plate at the beginning of the return stroke, produces a moment which urges feed plate 40 counterclockwise about the point of attachment and generally downward away from the bottom of the stack.

In accordance with the foregoing, it can be seen that more efficient feeding of the sheets is the result of increased complementary interaction between. the feeder plate and the stack.

Having thus described the invention in its best embodiment and mode of operation, that which is desired to be claimed by Letters Patent is:

1. An improved spring feeder assembly for sheet feeders of the type including a feed table for supporting the leading edge of a stack of sheets thereon, support means on said table for supporting the trailing edge of said stack above said table to define a space between said table and the bottom of said stack increasing gradually from the leading edge of said stack toward the trailing edge thereof, said spring feeder assembly reciprocable along said table in said space for advancing successive bottom sheets from said stack along a substantially horizontal feed path into adjacent processing machinery, comprising:

a feeder bar extending substantially across the width of said stack along the top of said table and reciprocable along said feed path; and

a plurality of flexible spring feeder plates spaced at intervals along the length of said feeder bar, said plates secured to said bar along a trailing edge thereof and extending upwardly therefrom toward a leading edge thereof,

gradually decreasing downward force on said sheet engaging portion during the return stroke of said feeder bar.

2. The spring feeder assembly of claim 1 in which:

said feeder bar includes a trailing edge tapered along its length at less than 45 with respect to a horizontal bottom surface of said bar; and

said spring feeder plates are secured to said bar substantially parallel to the taper on said bar and extend upwardly therefrom toward said leading edge of said bar. 

1. An improved spring feeder assembly for sheet feeders of the type including a feed table for supporting the leading edge of a stack of sheets thereon, support means on said table for supporting the trailing edge of said stack above said table to define a space between said table and the bottom of said stack increasing gradually from the leading edge of said stack toward the trailing edge thereof, said spring feeder assembly reciprocable along said table in said space for advancing successive bottom sheets from said stack along a substantially horizontal feed path into adjacent processing machinery, comprising: a feeder bar extending substantially across the width of said stack along the top of said table and reciprocable along said feed path; and a plurality of flexible spring feeder plates spaced at intervals along the length of said feeder bar, said plates secured to said bar along a trailing edge thereof and extending upwardly therefrom toward a leading edge thereof, said plates including a sheet engaging portion substantially above said leading edge of said bar, said portion including a ledge for supporting the trailing edge of a bottom sheet during advancement thereof and a lip portion extending above said ledge for engaging the trailing edge of said bottom sheet to advance the same, said bottom sheet exerting a gradually increasing downward force on said sheet engaging portion during advancement thereof for urging said lip portion into firm engagement with the trailing edge of said sheet, the next bottom sheet of said stack exerting a gradually decreasing downward force on said sheet engaging portion during the return stroke of said feeder bar.
 2. The spring feeder assembly of claim 1 in which: said feeder bar includes a trailing edge tapered along its length at less than 45* with respect to a horizontal bottom surface of said bar; and said spring feeder plates are secured to said bar substantially parallel to the taper on said bar and extend upwardly therefrom toward said leading edge of said bar. 